FWIW, I just ran into this Deutschland-Pass info, which might be worthwhile for someone traveling extensively in Germany. Can purchase between June 27 and August 31, for travel between June 27 and September 13.
For unlimited travel for one month:
349€ for over age 27
269€ for under 27
159€ for under 18
469€ for two adults together.
Add 100€ per person for 1st class travel.
This pass can be purchased online and at any Reisezentrum (travel center) in train stations.